Moderna announced that the first participant has been dosed in the Phase 2 study of the company's Omicron-specific booster candidate. Additionally, Moderna announced the publication of neutralizing antibody data against the Omicron variant six months following a booster dose in The New England Journal of Medicine.

While Omicron neutralization had declined 6.3-fold from peak titers at day 29 post-boost, levels remained detectable in all participants. Neutralizing titers against Omicron declined more rapidly than titers against the ancestral strain of the virus (D614G) which declined 2.3-fold over the same time period.

"We are reassured by the antibody persistence against Omicron at six months after the currently authorized 50 µg booster of mRNA-1273. Nonetheless, given the long-term threat demonstrated by Omicron's immune escape, we are advancing our Omicron-specific variant vaccine booster candidate and we are pleased to begin this part of our Phase 2 study," said Stéphane Bancel, Chief Executive Officer of Moderna. "We are also evaluating whether to include this Omicron-specific candidate in our multivalent booster program. We will continue to share data with public health authorities to help them make evidence-based decisions on the best booster strategies against SARS-CoV-2."

Phase 2 Study of mRNA-1273.529

This extension of an earlier study will evaluate the immunogenicity, safety, and reactogenicity of mRNA-1273.529 as a single booster dose in adults aged 18 years and older in two cohorts: individuals who previously received the two-dose primary series of mRNA-1273 with the second dose being at least six months ago (cohort 1), or who have received the two-dose primary series and a 50 µg booster dose of mRNA-1273 with the booster dose being at least three months ago (cohort 2). Participants in both cohorts will receive a single booster dose of mRNA-1273.529.

Moderna expects to enroll approximately 300 participants into each cohort of this study, which will be conducted at up to 24 sites in the U.S. Additionally, Moderna is evaluating the inclusion of mRNA-1273.529 in its multivalent booster program.